This invention relates to link and media access layer transaction initiation procedures in a communication system, and more particularly to such procedures in time slotted communication systems.
Link layer recovery protocols are used for error and loss recovery in data communication systems. Link layer recovery is especially crucial for wireless communications due to the particularly harsh loss and error characteristics of the link.
For cellular circuit data systems (eg. IS-130), supervisory frames are typically exchanged between the Radio Link Protocol (RLP) peer entities for connection establishment and for disconnection. The receiver RLP is not provided with advance knowledge of the duration of the connection or the last valid sequence number. The Mobile Data Link Protocol (MDLP) operation in CDPD is similar, and the protocol state is maintained across periods of inactivity.
Packet data transactions tend to be bursty with possibly long periods of inactivity between transactions. For mobile stations involved in intermittent transactions, with long inter-transaction times (even though each transaction may involve significant data transfer), maintaining RLP state information across long idle periods is a very inefficient use of network resources. Furthermore, the exchange of supervisory frames for a disconnect uses valuable air interface resources, and may result in some additional delay for establishing new connections. Therefore, a procedure for quickly, efficiently and gracefully ending transactions is desirable, especially when the link layer protocol is not situated back in the network. The GSM General Packet Radio Service (GPRS) uses a different approach. In the case of GPRS, bits are reserved in every Radio Link Control (RLC) block in order to indicate the end of a temporary block flow. This additional overhead in every RLC block is inefficient for long transactions, and leads to some loss in achievable throughput. The present invention is directed to overcoming, or at least reducing, the effects of one or more of the problems set forth above.
In accordance with the present invention, there is provided a system and method of implementing a radio link protocol completion process for a transaction oriented packet data communication system. The method performs the steps of determining a data backlog with a media access control layer controller and transmitting a BEGIN protocol data unit (PDU) containing a flag (a transaction size indicator) to a receiver. The method further performs the step of initiating a media access control layer transaction in response to the transmitting of the BEGIN PDU.
Also in accordance with the present invention, a transaction oriented packet data communication system is described. The system comprises a media access control layer controller for determining a data backlog in a media access control layer buffer a media access control layer transmitter for transmitting a BEGIN protocol data unit containing a flag (transaction size indicator) to a receiver. The system also includes a means for initiating a media access control layer transaction in response to the transmitting of the BEGIN Protocol Data Unit.
These and other features and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings and the appended claims.